156 A PRACTICAL TREATISE 



stopped; but when the salt has been washed in by the ram, 

 and partly decomposed by the mould, it adds to its force during 

 several followino- years. On rich land, when spread in small 

 quantities, it produces very sensibly favourable effects, though 

 of short duration; but if laid upon a poor soil, in an equal 

 quantity, it has been found wholly inefiectual. 



Nitre, or saltpetre, as it is more commonly called, though 

 of more powerful effect than common salt, is yet so rarely 

 employed as manure, and must necessarily be so limited in its 

 use for that purpose by the scantiness of the supply, that we 

 should hardly have adverted to it, except as matter of se- 

 condary interest to a few speculative farmers, had not our 

 attention been called to it by some papers which lately ap- 

 peared in the 'Quarterly Journal of Agriculture.' From 

 these we learn, that it has for some years past been used in 

 parts of Hertfordshire, and appears to be rather on the in- 

 crease ; that good crops have been produced by it, where crops 

 never Were good before; that it has been chiefly applied to 

 wheat, barley, oats, and grass in the early part of spring, sown 

 over the crops in the proportion of 1 to 1+ cwt. per acre; and 

 that the common price is about 25s. per cwt. 



As to the soil, which is the mast benefited by its application, 

 there is, as usual, much disagreement ; but it is generally re- 

 garded as favourable to chalky land, and the accounts all con- 

 cur in representing its effects upon grasses in general, but 

 particularly on clover, as being very striking. It is also 

 generally said to succeed best if sown in damp weather; that 

 it should be pounded till it will run through a wheat-sieve, 

 and may be sown by itself, but it is not uncommonly mixed up 

 with ashes. It is, however, of various qualities, which differ 

 exceedingly in strength, and make a proportionate diflerence 

 in its eflects upon the land, by inattention to which errors may 

 be occasioned in its application. From its analysis, as made 

 by Sir H, Davy, it appears that wheat contains more nitre than 

 any other protluct of a farm, and it was therefore expected to 

 be peculiarly favourable to the growth of that grain :* tlie fact, 

 however, se^ms at variance with this theory; for, altliough it 

 has generally occasioned an increase of straw', the yield of 



* It is known by chemists as nitrate of potass ; and, according to this 

 analysis, consists of one proportion of azote, six of oxygen, and one ofpot;is- 

 sum. Sir Humphry Davy says, that it may possibly furnish azote to form 

 albumen or glutten, in those plants that contain it. 



